1 /* Copyright (C) 2005-2020 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@redhat.com>.
3
4 This file is part of the GNU Offloading and Multi Processing Library
5 (libgomp).
6
7 Libgomp is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
11
12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 more details.
16
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
20
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
25
26 /* This is the default POSIX 1003.1b implementation of a semaphore
27 synchronization mechanism for libgomp. This type is private to
28 the library.
29
30 This is a bit heavy weight for what we need, in that we're not
31 interested in sem_wait as a cancelation point, but it's not too
32 bad for a default. */
33
34 #include "libgomp.h"
35
36 #ifdef HAVE_BROKEN_POSIX_SEMAPHORES
37 #include <stdlib.h>
38
gomp_sem_init(gomp_sem_t * sem,int value)39 void gomp_sem_init (gomp_sem_t *sem, int value)
40 {
41 int ret;
42
43 ret = pthread_mutex_init (&sem->mutex, NULL);
44 if (ret)
45 return;
46
47 ret = pthread_cond_init (&sem->cond, NULL);
48 if (ret)
49 return;
50
51 sem->value = value;
52 }
53
gomp_sem_wait(gomp_sem_t * sem)54 void gomp_sem_wait (gomp_sem_t *sem)
55 {
56 int ret;
57
58 ret = pthread_mutex_lock (&sem->mutex);
59 if (ret)
60 return;
61
62 if (sem->value > 0)
63 {
64 sem->value--;
65 ret = pthread_mutex_unlock (&sem->mutex);
66 return;
67 }
68
69 while (sem->value <= 0)
70 {
71 ret = pthread_cond_wait (&sem->cond, &sem->mutex);
72 if (ret)
73 {
74 pthread_mutex_unlock (&sem->mutex);
75 return;
76 }
77 }
78
79 sem->value--;
80 ret = pthread_mutex_unlock (&sem->mutex);
81 return;
82 }
83
gomp_sem_post(gomp_sem_t * sem)84 void gomp_sem_post (gomp_sem_t *sem)
85 {
86 int ret;
87
88 ret = pthread_mutex_lock (&sem->mutex);
89 if (ret)
90 return;
91
92 sem->value++;
93
94 ret = pthread_mutex_unlock (&sem->mutex);
95 if (ret)
96 return;
97
98 ret = pthread_cond_signal (&sem->cond);
99
100 return;
101 }
102
gomp_sem_destroy(gomp_sem_t * sem)103 void gomp_sem_destroy (gomp_sem_t *sem)
104 {
105 int ret;
106
107 ret = pthread_mutex_destroy (&sem->mutex);
108 if (ret)
109 return;
110
111 ret = pthread_cond_destroy (&sem->cond);
112
113 return;
114 }
115 #else /* HAVE_BROKEN_POSIX_SEMAPHORES */
116 void
gomp_sem_wait(gomp_sem_t * sem)117 gomp_sem_wait (gomp_sem_t *sem)
118 {
119 /* With POSIX, the wait can be canceled by signals. We don't want that.
120 It is expected that the return value here is -1 and errno is EINTR. */
121 while (sem_wait (sem) != 0)
122 continue;
123 }
124 #endif
125